Shock or tamper detection sensors are normally deployed within and/or as part of an overall security system which may be selectively deployed on/within a vehicle or on/within other objects which are desired to be protected. Particularly, these sensors are normally adapted to sense motion, shock and/or activity associated with and/or caused by undesired tampering, movement, theft, and/or attempted theft to the protected vehicle or object, and to produce an output signal indicative of this sensed and undesired activity. Many of these prior sensors included a movable magnet which was positioned in close proximity to an inductor or electrical "coil". As tampering type motion and/or "shock" was imparted to the sensor, the magnet was caused to move in relation to the relatively fixed electrical coil and an electrical signaling output current was produced which usually caused a siren, light, and/or other type of audio or visual signaling device to become activated, thereby providing a "positive" tampering signal which was often effective to "scare off" the potential thief and/or notify the owner of the protected object that a theft was attempted. Other types of prior sensors also include those which utilized a commercially available piezo type element to produce an electrical current output signal upon the detection of such tampering or induced and sensed shock or motion.
While these prior sensors provide tampering output signals, they suffered from some drawbacks. By way of example and without limitation, many of these prior sensors required a relatively large amount of electrical power in order to operate. This was and remains a particularly troublesome drawback since these prior sensors were and are normally employed as part of or an overall vehicle security system. As should be appreciated by those of ordinary skill in the art, vehicle security systems are normally and selectively "armed" or "activated" when the vehicle is parked (e.g. at an airport) for relatively long periods of time and are "powered" by the vehicle battery. Should the deployed sensor draw or require a relatively large amount of electrical power, the vehicle battery would ultimately and in relatively short order discharge leaving the vehicle owner stranded and resulting in an undesirable situation.
Further, many of these prior sensors, especially the piezo type, had variable temperature related sensitivities which caused their tamper detection characteristics to vary between the various seasons of the year (e.g. actually being relatively insensitive to tampering in very cold weather). Such performance inconsistencies were and are, of course, undesirable since the owner of a vehicle could never be sure exactly how the system would function and/or exactly how sensitive the sensor and the overall security system would be. The prior coil and magnet sensors are also known to be susceptible to electromagnetic interference which causes these sensors to malfunction, especially in areas having a relatively high amount of ambient electromagnetic energy.
Lastly, by way of example and without limitation, many of these prior sensors were and remain relatively costly, relatively easily prone to component failure, and relatively large and bulky.
There is therefore a need, and it is a principal object this invention to provide, a sensor which is adapted for use in and/or as part of a vehicle security system, which draws or requires a relatively low amount of electrical power, which is relatively low in cost, and which overcomes many of the drawbacks of prior sensors, including but not limited to those drawbacks and characteristics which have been previously delineated above.